TORONTO — Thursday night, Joe Girardi made the call every manager does when their team is holding on to a small advantage late in a game.

With a 4-2 lead, he phoned his bullpen and instructed his closer to warmup. For his first six seasons at the helm — except for most of 2012— Mariano Rivera would emerge to stretch and throw before galloping to the mound for the ninth inning.

But Rivera is enjoying retirement so it was David Robertson on Thursday and for the foreseeable future.

“It’s just different when you call,” Girardi admitted. “Yankee managers have been calling down for a long time asking for Mo.”

Robertson completed the task as efficiently as Rivera often did over his 17 seasons as the Yankees’ bullpen anchor. The right-hander needed just 12 pitches to retire the Astros in order and earn his ninth career save — but the first in the post-Rivera era.

And it was not his first save at Minute Maid Park. Robertson earned one in the final series last season against the Astros last season — and was loudly booed because he was no the retiring Rivera, who had been ruled out for the final set.

“I didn’t have runners all over the place,” Robertson joked. “So that was good.”

Robertson, 28, inherited the role without much competition. Even though Yankees brass refused to officially name him the closer until spring training, it was understood Robertson, an All-Star in 2011, was the next in line.

But he has repeatedly downplayed the significance of his promotion. To him, it’s the same role as his setup duties the last few years — just an inning later.

“I am just happy to get the first win under our belt,” said Robertson, whose appearance Thursday was his first in 2014. “I just tried to throw strikes. Having a two-run lead was nice.”

But the development is not an ordinary transition. Rivera was an icon in pinstripes. His 652 career saves and postseason brilliance have earned him the title of greatest reliever of all-time.

“I am sure it meant a lot to him,” Girardi said. “It’s not his first save, but it’s his first save without Mo.”

Thursday night’s victory also displayed a glimpse of how Girardi intends to use his new-look bullpen. Replacing Robertson in the eighth inning was Shawn Kelley and Adam Warren, the unit’s long reliever, worked 1 1/3 innings.

“The role doesn’t matter to me,” Kelley said. “The goal is the same whether I’m pitching the sixth, seventh or eighth. I need to get outs.”

Thursday night went as smoothly as possible for a bullpen entering the campaign with plenty of questions. The three relievers combined to throw 3 2/3 perfect innings. Robertson was just there to finish it off.

“I didn’t make it too dramatic so that makes it better,” Robertson said.